BACKGROUND OF THE INVENTION
(1) Field of the Invention
[0001] The present invention relates generally to Xenon spotlights, and is particularly
concerned with hand held or portable flashlights for use as terrestrial spotlights,
using air cooling for general high power long distance visibility in dark conditions.
(2) Description of Related Art
[0002] In recent years, the employment of non-lethal weapons has proven increasingly effective
in dealing with adversaries in a variety of law enforcement, corrections, military,
and physical security scenarios. In these areas, the goal of protection personnel
in most confrontations is to employ the lowest level of force necessary to control
the situation. Avoidance of collateral damage is increasingly critical for humanitarian
and public policy reasons. The possible levels of response force fall ranging from
verbal warnings, escalating to use of lethal weapons such as firearms. The possibility
of permanent injury or unintentional death increases as response level increases.
Also, as the level of force applied increases, adversaries will often escalate their
response thereby increasing the risk of injury to the security personnel. Any means
to minimize the level of interaction between the protector and the aggressor is therefore
of great value to security personnel and their adversaries alike. Consequently security
protection personnel need a response that assures their personal safety and eliminates
the threat of collateral damage to the maximum extent possible.
[0003] Ultra-bright light laser sources utilizing coherent light are claimed to offer a
means to control escalation of confrontations between security personnel and adversaries.
These light sources provide four levels of physical interaction with adversaries at
the "soft" end of the force continuum: psychological impact such as distraction and
fear; temporarily impaired vision (blindness); physiological response to the light
such as disorientation and nausea; and reduced ability to perform hostile acts such
as throwing objects, attacking, or aiming firearms. In addition, the adversaries'
response to the illumination can provide security personnel with threat assessment
in terms of intent and resolve. Examples of such devices are described in
U.S. patent nos. 5,685,636,
6,007,218 and
7,040,780.
[0004] Within the various application areas, there are many scenarios where a non-lethal
response with ultra-bright lights can be beneficial. These include perimeter protection
for government and industrial facilities, apprehension of armed and unarmed but violent
subjects, protection from suspected snipers, protection from assailants, and crowd/mob
control. Prison guards need non-lethal options in a variety of situations including
cell extractions, breaking up fights, and controlling disturbances. Another important
class of scenarios is that which limit the use of potentially lethal weapons because
innocent people are present. These include hostage situations, hijackings, protection
of political figures in crowds, airport security, and crowd control.
[0005] Collateral damage when using firearms or explosives on the battlefield is an increasing
problem. In time-critical scenarios, such as raids on hostile facilities or criminal
hideouts, where even a few seconds of distraction and visual impairment can be vital
to the success of the mission, visual countermeasures can enhance the capabilities
of law enforcement personnel.
[0006] Present devices utilizing coherent bright light sources are capable of a range of
effects on human vision which depend primarily on the wavelength, beam intensity at
the eye (measured in watts/square centimeter), and whether the light source is pulsed
or continuous-wave coherent light. There are three types of non-damaging effects on
vision using these sources; glare, flashblinding and physiological disorientation.
All of these technologies have application disadvantages.
[0007] The glare effect is a reduced visibility condition due to a bright source of light
in a person's field of view. It is a temporary effect that disappears as soon as the
light source is extinguished, turned off, or directed away from the subject. The light
source used must emit light in the visible portion of the spectrum and must be continuous
or flashing to maintain the reduced-visibility glare effect. The degree of visual
impairment due to glare depends on the brightness of the light source relative to
ambient lighting conditions. The disadvantage is that the aggressor is still capable
of inflicting harm and is not incapacitated.
[0008] The flashblinding effect is a reduced visibility condition that continues after a
bright source of light is switched off. It appears as a spot or afterimage in one's
vision that interferes with the ability to see in any direction. The nature of this
impairment makes it difficult for a person to discern objects, especially small, low-contrast
objects or objects at a distance. The duration of the visual impairment can range
from a few seconds to several minutes. The visual impairment depends upon the brightness
of the initial light exposure and the ambient lighting conditions and the person's
visual objectives. The major difference between the flashblind effect and the glare
effect is that visual impairment caused by flashblind remains for a short time after
the light source is extinguished, whereas visual impairment due to the glare effect
does not. The disadvantage it that the use of flash grenades can blind the user as
well as bystanders and dispensing methods may present fire or explosive hazards. Phosphorus
grenades that explode on impact, creating lots of noise, bright white light, have
the drawback that they produce high levels of heat capable of inflicting severe burns.
[0009] Physiological disorientation occurs in response to a flashing or strobe light source.
It is caused by the attempt of the eye to respond to rapid changes in light level
or color. For on-and-off flashing, the pupil of the eye is continually constricting
and relaxing in response to the contrasting light intensity reaching the eye. In addition,
differing colors as well as differing light intensities cause the same effect. The
disadvantage is epileptic fits may result and permanent neurological damage has been
reported. The National Society for Epilepsy states "Around one in two hundred people
have epilepsy and of these people only 3-5 % have seizures induced by flashing lights.
Photosensitivity is more common in children and adolescents and becomes less common
from the mid twenties onwards."
[0010] US 5243894 A describes a flashing light source for incapacitating individuals and forms the starting
point for the preamble of independent claims 1 and 6.
[0011] Other devices such as electrpmagnetic weapons like the Vehicle-Mounted Active Denial
System or VMADS being developed by Raytheon Missile Systems fires a focused, millimeter
wave energy beam to induce an intolerable heating sensation. The energy penetrates
less than 1/64 of an inch into the skin and the sensation ceases when the target moves
out of the beam. Unfortunately, such a device does not incapacitate or disable the
aggressor.
[0012] Thermal guns raise the agressor's body temperature to between 105 and 107 degrees
Fahrenheit, creating an instant and incapacitating fever. The magnetophosphene gun
can make a subject "see stars" by delivering what feels like a blow to the head. Such
a device has the potential to do brain and bodily damage due to excessive heat.
[0013] Eye-Safe light laser security devices such as those described in
U.S. patent nos. 5,685,636 and
6,007,218 employ a single coherent light laser or bank of lasers as the light source. The laser
can operate at any narrow wavelength band between 400 and 700 nanometers and provide
either continuous or repetitively pulsed (on-off flashing) light. Although effective
at stopping an aggressor, these types of non-lethal security devices could benefit
from improvements in the areas of safety in use, overall effective, susceptibility
to countermeasures, and cost. The disadvantage of coherent light lasers is that they
produce a very narrow beam that is difficult to target and manage its intensity to
avoid permanent eye damage. Furthermore the laser is susceptible to counter measures
such as filtered goggles that are wave specific. A fixed laser wavelength has the
added disadvantage of not shifting to correspond to the shift in sensitivity from
day to night (Photopic curve to Scotopic curve).
[0014] Consequently there is a need in the industry for a non-lethal, visual security device
that does not cause blindness or retinal damage, present a burn hazard, pose a fire
or explosive hazard, cause seizures or brain damage, cause permanent harm to the target
or others, that incapacitates the aggressor so that they may be easily apprehended,
is capable of low cost manufacture, is relatively resistant to countermeasures, may
be easily directed at one or more aggressors simultaneously, can incapacitate a target
at great distances and renders the aggressor incapable of further aggression for a
period of time to enable capture.
BRIEF SUMMARY OF THE INVENTION
[0015] It is an object of this invention to provide non-lethal, non-eye-damaging security
devices based on intense light and, more particularly to provide non-lethal, non-damaging
security devices using incoherent light to cause visual impairment and disorientation
through illumination by constant focus reflected bright, visible light beams.
[0016] According to the present invention, a device and a method for incapacitating one
or more target individuals according to the claims 1 and 6 are provided. Optionally
the device includes a high tension feed wire to the cathode end of the Xenon lamp,
with the lamp electrode gap at the focus of the reflector, a power supply input for
driving the lamp, and a cooling mechanism for maintaining constant optimum lamp anode
temperature as desired. The spotlight also incorporates a safety switch, elapsed hour
meter and low battery indicator light.
[0017] The electric arc lamp contains a Xenon gas which produces a high intensity light
(plasma) ball. The adjustment mechanism relegates lamp tilt relative to the central
axis of the reflector to the lamp manufacturer, and the reflector to be moved axially
back and forth relative to the fixed plasma ball, until the focal position is found.
This arrangement also permits stable focal adjustment with no added mechanical tolerancing.
At this point the lamp is in position. These adjustments are made during or after
manufacture of the spotlight.
[0018] In the preferred embodiment of the invention the power supply is connected to the
lamp via electronic circuitry for controlling the lamp operation under precise conditions.
This includes a substantially constant light output for an input voltage range continuously
variable over 10.5 to 14.5 volts.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0019] The present invention will be better understood from the following detailed description
of a preferred embodiment of the invention, taken in conjunction with the accompanying
drawings, in which like reference numerals refer to like parts, and in which:
FIG. 1 (A) is a side view of a spotlight assembly according to a preferred embodiment
of the invention, (B) is a perspective view of a spotlight assembly partially broken
away to illustrate the components of the spotlight;
FIG. 2 is an exploded view of the spotlight's focusing and front section assembly
mechanism.
FIG. 3 is a block diagram of the electronic circuitry for the spotlight of FIGS. 1
and 2; and
Fig. 4 is a schematic of one possible circuit configuration for the circuitry of Fig.
3.
Fig. 5 is a schematic of the proposed physiological effect of the light on a target
individual.
DETAILED DESCRIPTION OF THE INVENTION
[0020] Unless defined otherwise, all terms used herein have the same meaning as are commonly
understood by one of skill in the art to which this invention belongs. In the event
that there is a plurality of definitions for a term herein, those in this section
prevail.
[0021] The term "incapacitating" as used herein refers to the capability of limiting the
actions of a target by causing disorientation, reducing cognitive abilities, interfering
with vision, and/or fine and gross motor skills for a period of time enabling capture
or disarming of the target without the physical damage presently observed with coherent
light source devices.
[0022] The term "adjustable mounting means" as used herein refers to any mounting configuration
that allows the user to focus the beam of the electrical arc lamp to assure that the
target at a given distance from the user receives sufficient intensity light to cause
incapacitation.
[0023] The term "electrical circuit means" as used herein refers is any means by which the
electric arc lamp may be activated in an effective and efficient manner to produce
the desired affect on a target. Preferably the electronic circuit comprises at a minimum
a switch connecting the power source to the electric arc lamp for turning the lamp
on or off as desired. Other elements may be incorporated into the electronic circuit
means to increase the effectiveness under certain anticipated or expected conditions.
For example, the distance of a target may vary substantially. Under these circumstances
it may be beneficial to incorporate an automatic focusing system for the beam to increase
the chance of effectiveness. Such a system could include an Infrared range finder
for determining the distance to a target allowing adjustment of the beam intensity
prior to illumination to assure the desired affect is obtained on the target. Other
mechanisms such as a mechanical shutter could be incorporated for pulsing the beam
at the target.
[0024] The term "incoherent light" as used herein refers to light that is not produced from
a coherent light source such as a laser. Ordinary light from the Sun or light bulbs
consists mainly of light waves of many different wavelengths and is considered incoherent
light. What light there is of the same wavelengths tends to be randomly phased as
opposed to coherent light wherein the waves are in phase with each other.
[0025] The term "means for determining distance" as used herein refers to any means for
estimating, approximating or determining the distance between two points wherein one
point is the device utilizing the means for determining distance and the other point
is the target. One example of such a device is an Infrared range finder.
[0026] The term "means for releasing" as used herein refers to any method that may be employed
to release a beam of light from the device of the present invention in a single continuous
blast, pulse or flash. One example of such a means would be a shutter affixed over
the lens of the device that can be activated manually or electronically. Upon activation
the louvers of the shutter are quickly rotated open and then rotated to the closed
position to emit a beam of light at the target.
[0027] The present invention is a non-lethal, less-than-lethal, or less-lethal hand-held,
mobile or stationary weapon that uses incoherent visible white light to temporarily
disorient, stun, incapacitate, reduce the cognitive abilities of, or otherwise control
and limit the actions of one or more persons, assailants, perpetrators, intruders,
or adversaries, without causing permanent injury.
The invention produces luminous flux with sufficient photon content that, when applied
to a target, enters the target's eyes and saturates the ocular retinal cones. It is
postulated that this event produces a chemical reaction via the target's eighth nerve,
possibly the pineal organ, posterior parietal cortex, inferior temporal cortex, and
angular gyrus that temporarily disorients, stuns, incapacitates, reduces the cognitive
abilities of a target, and otherwise controls and limits the actions of the target,
including loss of control of fine and gross motor skills, without causing permanent
injury to the target, as shown in Figure 5.
[0028] The exact mechanism for the incapacitation is not fully understood, but appears to
extend beyond the transient decrease in vision that occurs in individuals when they
are subjected to a bright flash. There are more than 2 million neurons that comprise
the optic nerve. They constitute about 40% of the total number of nerves entering
or leaving the central nervous system via the cranial and spinal nerves. While the
majority of the neural information is destined for the visual cortex, the visual system
also provides a significant input for balance and muscle control. It is plausible
that the incapacitation is the result of a sensory overload of the brain.
[0029] The incapacitating effect occurs within 2 seconds. The illuminated target is observed
to temporarily lose the ability to see and to lose control of gross and fine motor
skills for approximately 10 minutes with full recovery within 30 minutes. The result
is disorientation and loss of balance effectively incapacitating the target(s). No
physical damage to the visual system has been observed following exposure to a visible
light source with appropriate intensity.
High Intensity Incoherent Light Assembly
[0030] Referring to Figures 1-4 the drawings illustrate a high intensity spotlight according
to a preferred embodiment of the present invention. The spotlight is of a portable
or hand held design and includes a outer, generally cylindrical casing of standard
flashlight-like dimensions (for example, 6.5 inch head diameter x 13 inch length)
having a housing
1 in which electronic circuitry
6 for operating the spotlight is mounted, and an enlarged head portion
X. The housing
1 also contains screw threads on the perimeter of it's head portion
X for paraboloid reflector
38 positioning, a thermostatic switch, cooling fan
21, low battery indicator light
146, safety switch
145 and elapsed time meter
151.
[0031] In one preferred embodiment of the present invention the housing is hollow and contains
all the spotlight components. Referring to Figure 1, The head portion
X has a window lens
16 opening at its outer end for transmitting a light beam, and a paraboloid reflector
38 is mounted in the head portion
X to face the window lens
16 opening. The paraboloid reflector
38 is preferably of electroformed nickel treated with highly reflective coatings like
Aluminum-Quartz, Rhodium, or other dielectric thin film layers used to achieve desired
absorption and reflectance properties. The paraboloid reflector
38 has an aperture
14 bored at its vertex for insertion of a Xenon arc lamp
15 and a cathode feed wire. The embodiment shown is the best method and can be scaled
for higher power lamps. The 75-Watt Xenon arc lamp emits a beam through the window
lens opening. The lens opening is preferably covered with a disc of specially coated
glass
16 which is AR (anti-reflective) coated and has pre-determined properties to absorb
ultraviolet light rays emitted by the Xenon arc lamp
15 below 400 nanometers wavelength which is harmful to the eyes (the UV screen is not
required but is recommended for safety). The combination of AR Coating and reflector
reflectivity results in converting ~1200 Lumens generated into a beam of ~1000 Lumens
with a ∼1 degree beam spread.
[0032] Referring to Figure 3, The lens glass
16 is cradled in a U-channel gasket
27 that is secured in place by stand-off posts
37 (Figure 4) and in contact with outer bezel
28 positioned over the window lens
16. Outer bezel
28 is threaded to the outer end of the housing head portion, and by turning the bezel
28 (and simultaneously the retainer threads), the unit is focused as the window lens
gasket and paraboloid reflector
38 rotate together with respect to the stationary Xenon arc lamp
15.
[0033] Referring to Figure 1, the paraboloid reflector
38 has an outer rim
13, which is seated against an annular shoulder
12 on the inner surface of the housing
1. Two O-ring seals
41 and
42 ensure the paraboloid reflector
38 is under compression between the U-channel gasket
27, and reflector retainer
17. The base plate
10 has a central opening (larger diameter bore portion
49 and smaller diameter bore portion
52) in which collet
34 for Xenon arc lamp
15 is mounted via the collet nut
53.
[0034] The base plate assembly
75 is in several parts, and is illustrated in more detail in Figure 4. Assembly includes
a reflector retainer
17 secured in the opening of the base plate
10 via threads (matching inner threads
45 and matching outer threads
46) of equal pitch to fastening clips
31. In this way, the reflector retainer
17 serves the purpose of a focusing mechanism for the Xenon arc lamp
15, and allows air to flow through air holes
43 for removing heat dissipated by the assembly
75 and reflector retainer
17 before exiting from air exit ports
30 of bezel
28. Figure 4 shows connecting wire
39 threading glass capillary high temperature insulator
40, threading base plate assembly
75 through cathode wire feed-through hole
50, threading the reflector retainer
17 and paraboloid reflector
38 before being attached to the cathode connector
32 of Xenon arc lamp
15. The collet
34 has an outer chamfer
35 of conical outer diameter (and in which the anode portion of the lamp fits snugly).
Mating seating surfaces on the assembly
75 accommodates mounting of the collet
34 through the larger diameter bore portion
49 with its threaded stem
36 projecting through the smaller diameter bore portion
52. Threaded stem
36 receives a similarly screw threaded collet nut
53 at its outer end in which the anode end of the Xenon arc lamp
33 is secured. Lens
16 is held by bezel
28 and U-channel gasket
27 with fastening clips
31, stand-off posts
37, screws (not shown) projecting through fastener holes
44 and attaching to threaded fastening clips
31; thereby compressing the reflector assembly against reflector O-ring
42, and the mating machined grooves for the O-ring, within reflector retainer
17.
[0035] Referring to Figure 1, this mounting arrangement allows the position of the paraboloid
reflector
38 relative to Xenon arc lamp
15 to be precisely adjusted, while allowing air flow across the spokes
9 and back side of the paraboloid reflector
38 and through air holes
43, before being exhausted through air exit ports
30 to the atmosphere. The paraboloid reflector
38 is moved axially in or out for longitudinal adjustment of the reflector position,
by rotating the bezel
28 clockwise or anti-clockwise. The collet
34 can not be tilted in any direction for transverse adjustment; rather the axial symmetry
of the lamp is relegated to the lamp manufacturer. Hence the focusing mechanism has
minimal variation with time, temperature, shock, etc. The focusing adjustments are
made during manufacture of the spotlight and then as needed by the user. The paraboloid
reflector
38 position is adjusted until the gap between the electrodes is located precisely at
the focus of the reflector, to produce a high candle power, tunnel-like beam of light,
which is as close as possible to parallel, with little divergence. The optimum reflector
position is detected by fixing the beam on a target, and (by rotating the bezel) adjusting
the reflector position until the diameter of the spot is at a minimum.
[0036] Referring to Figures 1 and 4 the assembly
75 is designed with pre-determined mass and surface area to remove heat generated both
by the Xenon arc lamp
15 and electrical circuitry. The assembly
75 is also designed to have the heat capacity and geometry required to achieve substantially
constant anode temperature of approximately 185°C. Referring to Figure 4 and 6, assembly
75 has three mounting holes
47, 48 and
51 which hold power diode
D12, thermal switch (thermostat) and transistor
Q10. Thermostat switch is responsible for achieving the constant anode temperature of
Xenon arc lamp
15 in conjunction with cooling fan
21 (see Figure 2) and system pressure drop vs. air flow requirements for air entering
housing
1 through air inlet ports
54, sucked through end cap
55 and filter material
22 by the cooling fan
21. Rear end cap
23 is secured through end cap holes
55 by two fastening screws (not shown), and the cooling fan
21 is fastened by screws (not shown) to the remaining four holes
56. The metal baseplate
10 holding the Xenon arc lamp
15 and collet
34 is of conductive material, for example aluminum. The aluminum must be massive enough
to store sufficient heat, yet with enough surface area to dissipate heat generated.
Referring to Figure 1, the baseplate
10 also serves as the electrical connection to circuitry
6 using anode connecting wire
57.
[0037] The Xenon arc lamp
15 can be seen in more detail in Figures 1 and 4. The paraboloid reflector
38 is optimized for a 75 Watt Xenon arc lamp
15, collecting 90% of the light emitted at the reflector focus, while allowing only
~5% of the light emitted to pass through the hole at the vertex. Similarly, the length
of the paraboloid reflector
38 is pre-determined to ideally collect 95% of the light reflected off the reflector.
The optimum vertex hole size is ~14.0 mm diameter, with ∼0.32 inch focal length and
~4-inch clear aperture; based upon the polar radiation plot for a Ushio (Cypress CA)
UXL-75Xe short arc lamp. Another manufacturer's 75-Watt Xenon arc lamp could be used
instead, but the radiation pattern will be somewhat different. For example, Osram-Sylvania
(Danvers MA), Philips (New York, New York) and many other manufacturers make similar
75 Watt and higher (more than 4000 Watts) Xenon arc lamps.
[0038] As mentioned above, the anode connection to the power supply and electronic or control
circuitry
6 is made via base plate
10. Referring to Figure
4, The cathode connection is made via conductive end cathode clip
32 on the distal end of the Xenon arc lamp which is secured via conductive connecting
wire
39, through glass capillary insulating tube
40, and through cathode wire feed -through hole
50 in the baseplate
10, where it connects to the power supply circuitry shown in Figures 5 and 6. Cathode
end clip
32 has some resilience to produce a spring effect, while welding the connecting wire
39 to the lamp cathode clip
32 achieves a reliable connection. The conductive connecting wire
39 is flexible to avoid any mounting torque on the cantilevered end of the lamp (cathode
remains free from strain). Conductive connecting wire
39 is coated with flexible insulation to withstand a ∼12kV ∼0.5-microsecond voltage
pulse in the empty space between the conductive connecting wire
39, and hole at vertex of paraboloid reflector
14 shown in Figure 1 (insulation thickness may be increased for higher wattage Xenon
arc lamps requiring larger peak starting voltages). Conductive connecting wire
39 is coated by flexible insulation which can withstand temperatures in excess of 200°C
continuously. In the event of impact or vibration, the cathode end of the lamp can
vibrate with less risk of damage. For 75-Watt Xenon arc lamps, a length of nickel
wire
58 surrounds the length of the lamp to improve the lamp starting performance and stability
of the ensuing arc by serving as an equipotential with magnetic susceptibility. Large
Xenon arc lamps (i.e. 2500 Watts) may need an externally applied magnetic field in
place of the nickel wire
58 for stable operation. The Xenon arc lamp has only a very short gap
59 between its electrodes, normally on the order of 0.8 millimeters for a 75 Watt lamp
(and for reference, 3 mm for a 1000 Watt lamp), and it is this gap which is centered
on the focus of the reflector in order to achieve the desired, substantially parallel,
high intensity light beam.
[0039] As illustrated in Figure 2, the housing
1 comprises a hollow tubular member and contains the cooling fan
21 and printed circuit board
24, containing all electronic circuitry described in Figures 3 and 4 for operating the
75-Watt Xenon arc lamp under precisely controlled conditions, as explained in more
detail below. The housing
1 has air inlet and exit ports
54 and
30 (Figure 1) where coolant air cycles through the system to remove heat from the baseplate
10 and paraboloid reflector
38 surfaces while keeping the lamp anode
33 at substantially constant 180°C. Referring to Figure 2, the circuit components are
provided on printed circuit board
24 mounted in the casing
1. Referring to Figure 1, a thumb switch 2 is imprinted for the user to read "Off-On-Start"
which can initiate and then terminate operation of the circuitry to activate the lamp
at the push of a button. The switch
2 also protects against the circuitry from igniting the lamp when it is first plugged
into the battery if the switch has been left in the "On" position. The switch
2 has three physical positions "Off", "On" and "Momentary-On" (START).
[0040] Referring to Figure 2, detachable end cap
23 seals the back end of the casing
1 while retaining cooling fan
21 and filter material
22. Removable front end cap
29 (see Figure 3) seals the front end of the casing
1 to attenuate high frequency radiation generated by the Xenon arc lamp
15 during ignition transients. Referring to Figure 1, a power cord hole
5 exists in the end cap
23 for receiving power to operate the unit, from an (15-Ampere Slo-Blo fused) automobile
cigarette lighter, external 12-Volt battery power pack, or a 10.5V-14.5V power supply
for example. A cord strain relief connection (not shown) holds the power cord snugly
through power cord hole
5.
[0041] The inner wall of the casing
1 is coated with an electroplated shielding along its whole length, for attenuating
the radiation generated by the electronic circuitry
6. Radiation generated by the Xenon arc lamp
15 during ignition is attenuated by conductive end cap
23 of Figure 2. Referring to Figure 1, the casing
1 also contains means for connecting to the casing the Spyder spokes
9, an elapsed time meter 4, a low battery indicator light
3, and cooling fan
21 of Figure 2. The casing has two grooves or snap-in channels
29 on its inside opposing sides into which the printed circuit board
24 is press-fit to the opposite side edges of the casing
1 to secure it in place. Spaced buckle holes may be mounted on the outside of the housing
for receiving a shoulder strap (not illustrated) for carrying the spotlight. The shape
of the housing
1 maybe such that it prevents rolling of the housing if the spotlight is placed on
a flat surface. There may be two threaded holes on the side of the housing used to
attach the spotlight to a yoke (not shown). There may also be a threaded hole on the
bottom of the housing to attach a camera or gun mount (not shown).
[0042] The circuitry for controlling operation of the Xenon arc lamp will now be described
in more detail with reference to Figures 3 and 4.
[0043] Referring first to the block diagram of Figure 3, the circuit for a 75-Watt Xenon
arc lamp
15 has suitable 10.5-14.5 Volt power supply
144, which is connected via power cord hole
5 (see Figure 1) and which may comprise a battery, a vehicle lighter, or a power converter
from a wall socket, for example.
[0044] The circuit shown in Figures 3 and 4 provides a substantially constant power to a
75-Watt Xenon arc lamp
15 for a plurality of input voltages. The power delivered to the lamp is under control
of a servo loop
149. The intent is to allow for operation from a 12-volt battery (e.g. Lead-acid Nickel-Cadmium,
or Lithium-ion), or from an automobile charging system which typically operates between
about 10.0 and 14.2 Volts. Usage of Nickel-Cadmium (Ni-Cd) batteries are not recommended
for reliable operation of the low battery indication because Ni-Cd batteries have
a more constant output voltage than the lead acid type during discharge. The lamp
is programmed to shut-down when the circuit input voltage drops below 10.5 Volts in
order to protect the battery from damage. The cable which connects the battery to
the device has low resistance. A practical battery connection extends above 50 feet
with one Volt average drop across a 14-gauge stranded copper wire pair. 5 feet of
16-gauge wire also corresponds to 1 volt drop across the power cable during steady
operation of the lamp.
Modes of Operation
[0045] There are several modes of operation to be described which are outlined below generally
in the order, which they occur:
- 1. Connecting the battery
- 2. Engaging the on/off switch
- 3. Spark gap discharge and lamp ignition
- 4. Servo loop stabilization
- 5. Thermal management and cooling
- 6. Low battery detection and shutdown
- 7. Automatic shutdown upon lamp failure
- 8. Average lamp power and operating frequency adjustment
- 9. Safety switch
- 10. Low battery indicator
- 11. Elapsed time meter
Mode 1. Connecting the battery.
[0046] It is assumed that the circuit is fully discharged before the battery is connected.
Referring to Figure 4, it is also assumed that the on/off switch is in the "off" (SW
on open, SW
off closed) position when the battery is connected to the circuit. Upon connection of
the battery to the circuit, capacitor
C10 charges up to the battery voltage.
C10 is a relatively large capacitance for supplying filtered current to the power switching
transistor
Q10. Because the on/off switch is in the open position, the base-to-emitter voltage of
the
Q10 remains low so no current flows, and the collector of
Q10 stands off the battery voltage. The cooling circuit
152 remains powered up even when the switch is turned off.
Mode 2. Engaging the on/off switch to turn on the light.
[0047] U3 (the regulating pulse-width-modulator (PWM) is a well-known integrated circuit such
as the LT/SG1524. When the switch is first turned on, the regulator output (
U3 pin 16) tends quickly toward 5 Volts and charges filtering capacitors
C24, C25. Before pin 16 of the PWM reaches 5 Volts however, its oscillator has not yet begun
so consequently pin 12 of
U3 is initially in a high impedance state. Initially, open-collector output pins 1,13
of
U1 are at high impedance. Before the PWM starts to oscillate, a current conducts through
R18. The collector current rise time of
Q14 is initially slowed by Resistor
R69-C69 which prevents excessive current through
Q10 until the PWM begins oscillating. When the voltage on pin 16 of the PWM finally rises
to 5 Volts, the servo
149 and latch
147 can then engage. A voltage at pin 2 of
U3 controls the duty cycle of it's output at pin 12. The voltage at pin 2 initially
achieves it's minimum value determined by voltage divider
R96, R97. A minimum value at PWM pin 2 corresponds to a maximum duty cycle. Thus upon startup
(when oscillation begins), maximum duty cycle is applied to the base of
Q10 to assist in starting the lamp.
[0048] Initially the latch
147 is held in the "off" position as defined by high impedance at pins 1,13 of quad comparator
U1.
U1 is comprised of operational amplifiers
A2, A3, A4 and
A6. During ignition and before the Xenon arc lamp is ignited, the voltage at pin 7 of
U1 remains greater than the voltage at
U1 pin 6, due to the difference in time constants
R64-C38 and
R70-R68-C40. Also during startup the voltage at pin 10 of
U1 remains less than the 2.5V setpoint voltage at pin 11 of comparator
U1 (R54-R56). The effect is for the output (
U1 pin 13) to remain at high impedance (off) until several seconds have elapsed after
the on/off switch was engaged. If the lamp still has not ignited after the time determined
by
R52-C36, then the latch output will switch to low impedance at pins 1,13 when pin 2 of
U1 goes high (5V) after time constant
R52-C36 has elapsed and the lamp still has not ignited. During ignition,
U1 pin 14 goes high. If the lamp ignites,
U1 pin 14 goes low. If
U1 pin 2 goes high due to
R52-C36 time constant before
U1 pin 14 goes low (lamp started) then the latch
147 will "set" and disable the lamp while placing the circuit on standby after
C40 discharges to near zero exit Volts. Low impedance at pin 1,13 of
U1 disables the PWM (and the power transistor
Q10) by shunting the output of
U3 pin 12 to ground through D20. Subsequently, a low value at
U1 pin 13 prevents lamp ignition until after the thumb switch has been shut off.
Mode 3. Spark-gap discharge and lamp ignition.
[0049] When the lamp has not yet ignited, capacitor
C14 is charged to ~100 Volts through inductor
L3 and rectifier
D12 as follows: When
Q10 conducts, current rises in
L3 and flows to ground through the collector of
Q10 for the "on" portion of the duty cycle determined by the PWM
148. When the PWM changes to it's "off" portion, transistor
Q10 turns off thus forcing current flowing through
L3 to divert into
C14 through diode
D12. Since the Xenon arc lamp is not conducting, negligible current flows into the lamp
as capacitor
C14 continues charging toward ∼100V.
[0050] Concurrently, as the lamp has not yet ignited, capacitor
C20 charges through diode
D10 and current limiting resistor
R20 using the magnetic coupling and turns ratio of
L3-L4. When the voltage across
C20 exceeds 470V, spark gap
EC1 arcs-over, providing a ∼0.5us FWHM, low-impedance discharge of 2500 Amperes peak,
chiefly due to the series impedance of capacitor
C20, spark gap
EC1 and transformer winding
L1. The fast discharge of
C20 through
L1 and
EC1 causes -12kV to be applied across the lamp electrodes due to the magnetic coupling
and turns ratio of
L1-L2. When -12kV appears at the lamp cathode, the Xenon gas becomes ionized at approximately
10~50 Amperes, 12kV and then capacitor
C14 discharges through the lamp. The initial ~500 kW discharge of
C14 into the lamp provides necessary cathode heating to sustain an arc. With the arc
sustained, the lamp drops to a low impedance state and peak collector voltage across
Q10 drops significantly from 110V to 55V. Thereafter a 55V peak on
Q10's collector during steady state lamp operation only charges
C20 to 350 Volts, which is well below the arc-over threshold of
EC1. Hence as soon as the lamp ignites, the 470 Volt spark gap
EC1 can not fire again. A properly working circuit generates only one high power -12kV
ignition pulse at the Xenon arc lamp cathode before it ignites. If the lamp does not
ignite on the first pulse (due to wear and temperature), the collector of
Q10 will remain at 110V peak until a) the lamp ignites or b) the latch sets (thereby
placing the spotlight on standby) after unsuccessful ignition of the lamp over a few
seconds time at a pulsed ignition rep-rate of approximately 3∼10 Hz. When the lamp
is not conducting and the peak collector voltage of
Q1 is at 110V the voltage at pin 9 of
U1 becomes greater than the 2.5V setpoint at
U1 pin 8 as described above, which will cause the latch
147 to be set if the few-second time constant of
R52-C36 has elapsed and the lamp has not yet ignited. If lamp does ignite, the reduction
of 110V peak collector voltage to 55 Volts peak brings pin 9 of
U1 below the 2.5V setpoint (
U1 pin 8) so pin 10 of LM393 remains low and the latch
147 does not set.
[0051] During steady state operation when the lamp is on, the 20 KHz periodic behavior is
as follows: prior to pin 12 of
U3 going high (during the "on" portion of it's duty cycle),
Q10 is not conducting. When
Q10 is not conducting, the lamp current source is due to monotonically decreasing series
current flowing through
L3 and
D12. The current flowing through
D12 splits and flows into the lamp while simultaneously re-charging capacitor
C14. As soon as capacitor
C14 is fully charged, the PWM transitions to it's "on" cycle (
U3 pin 12 goes high) and transistor
Q10 shunts the current flowing through
L3-D12 to ground through the collector of
Q10. The series current through
L3, Q10 begins to rise monotonically as energy is stored in the magnetic field of
L3 for delivery to the lamp and
C14 during the next half-cycle. Simultaneously when the current through inductor
L3 increases, the voltage across capacitor
C14 decreases when it is delivering current to the lamp (as
D12 is reverse biased during that time interval). As
C14 is decreasing in voltage during the PWM "on" cycle, inductor
L2 provides a substantially constant, 6 Ampere peak current with only 0.5 peak Amperes
current change through the lamp. As
U3 pin 12 reaches the end of it's "on" cycle, series current through
L3, Q10 reaches ~22 Amperes. Concurrently, capacitor
C14 is discharged and diode
D12 becomes forward biased which begins to divert current away from the collector of
Q10 even before
U3 pin 12 goes into it's "low" half cycle and cuts off base current to the
Q10. At this point the process begins again with the current through
L3 monotonically decreasing as it delivers energy to the lamp and
C14. The switching cycle repeats at approximately 20 KHz to achieve constant 80 Watts
average lamp power. Higher operating frequencies translate to more power loss in the
circuitry, where lower operating frequencies are in the range of human hearing and
mechanical camera shutter speeds. It should be noted that a power MOSFET, IGBT, GTO
or other power switch could be substituted for the Darlington transistor pair
Q12, Q10 in order to reduce conduction and switching losses; with minimal changes to the circuit.
Mode 4. Servo loop stabilization.
[0052] Referring to Figure 4, when the lamp has ignited, the servo senses the voltage V
z generated at the collector of
Q10 with voltage divider
R6-R65. The servo compares the voltage V
z against the setpoint V
ref and then integrates the resulting comparison pulses to increase or decrease the duty
cycle of the PWM. Ideally the peak voltage across
Q10 is 55 Volts which yields an average lamp power of ~80 Watts. If the peak voltage
at the collector of
Q10 remains at 55 Volts when the input power supply voltage is in the range 10.5V-14.5V
then the average lamp power remains substantially constant (nominally within 5% of
its mean at 20 KHz, but can be made arbitrarily small by increasing the value of
L2). The control loop input voltage V
z is compared with V
ref, which then generates a square wave pulse at pin 1 of quad comparator
U2 (assuming the PWM is in operation and the latch is off with
U1 pin 13 high).
U2 is comprised of operational amplifiers
A1, A5, A7 and
A8. The square pulse at pin 1 of
U2 is divided by the combination of resistors
R96,R97, and
R98 so the voltage V
y remains within the PWM's useful range of input voltages 2.5V-3.5V (the PWM input
at pin 2 responds to the range of 2.5V-3.5V). Resistor
R95 and capacitor
C68 filter the signal V
y so a DC level V
x is generated and applied to the duty cycle adjustment pin 2 of the PWM
(U3). Resistor
R99 provides a discharge path for
C68, which makes the circuit less sensitive to probing for measurement purposes. The resulting
electrical feedback (servo) process causes the duty cycle to vary from maximum to
minimum as the circuit input voltage respectively varies from minimum to maximum.
Mode 5. Thermal management and cooling.
[0053] There are three devices, which dissipate relatively large amounts of heat when the
75-Watt lamp is on: the lamp, transistor
Q10 and power diode
D12.
Q10 and
D12 together generate 25 Watts of heat, while the Xenon arc lamp also generates more
than 25 Watts of heat. Therefore at least Watts of heat is required to be dissipated
by the baseplate
10 when the Xenon arc lamp
15 is delivered with a constant power of 80 Watts. It is also required to maintain the
baseplate
10 temperature at a level corresponding to a lamp anode temperature of approximately
185°C. Since the thermostat switch is connected to the baseplate
10 mounting hole
51 (Figure 4), it senses a pre-determined temperature window of on and off temperatures.
The thermostat powers the fan
21 directly from the battery so it will operate independently of the on/off switch.
If the lamp is shut off then the fan circuit will continue to operate until either
the lamp anode temperature decreases below ∼180°C as sensed by the thermostat or if
the battery becomes disconnected. The fan will operate when the thermostat switch
reaches an equivalent anode temperature Ton ∼190°C and the fan will shut off automatically
when the thermostatic switch cools to an equivalent anode temperature T
off ∼180°C. Since the thermostat is mounted in a predetermined position for sensing a
proportionate temperature to the Xenon arc lamp anode, the thermostat senses a corresponding
lamp temperature, and turns the fan on to blow air across the baseplate (heat sink)
as needed. As the baseplate cools from the fan air blowing on it, the attached thermostat
switch cools back toward temperature T
off. When the lamp is off, the fan will cool the baseplate faster than when the lamp
is on.
Mode 6. Low battery detection and shutdown.
[0054] Rechargeable batteries can degrade in performance if allowed to deep-discharge. Deep-discharge
is defined here to be below ~10.5 Volts for a 12 Volt, 12 Amp-Hour rechargeable battery
sourcing 13 Amperes. Thus to stay well above deep discharge the latch
147 (pin 1 of
U1) sets and its output drops to low impedance if circuit input voltage drops below
~9.5 volts (accounting for ~1 volt drop across the power cord during steady state
operation), and the output of the PWM (
U3 pin 12) is shunted to ground through
D20 when the latch
147 is set. Also when the latch sets (
U1 pin 1 goes low), and
C40 discharges to ground through
R94-D22. Once the latch is set, the lamp can not re-start until the on/off switch is momentarily
disengaged to the "off" position and then re-engaged to the "on" and then "start"
position. When the on/off switch has been turned "off",
C36 discharges through
D14, R31 to ground. Therefore the lamp can not be turned on and off too rapidly by the thumb
switch faster than approximately one time constant of the
R31-C36 resistor-capacitor pair.
Mode 7. Automatic shutdown upon lamp failure.
[0055] There is a chance that a Xenon arc lamp will explode under certain conditions and
become an electrical open-circuit. There is also a possibility for a lamp electrode
to become detached due to shock or electrical contact failure. If such a condition
should happen while the lamp is on then the peak collector voltage of
Q10 increases from 55V peak to its maximum peak value of 110V. The spark gap
EC1 would then begin firing at approximately 3~10 Hz repitition-rate until the time constant
R22-C22 charges
C22 and
U1 pin 9 exceeds the 2.5V setpoint at
U1 pin 8. Since many time constants
R52-C36 elapse after the lamp has reached steady state operation, the latch immediately sets
and puts the spotlight on standby if a lamp connection is interrupted; since
U1 pin 14 goes high (due to the 110V peak collector voltage of the
Q10) which sets the latch
14.7 (
U1 pin 1) low and puts the spotlight on standby.
Mode 8. Average lamp power and frequency adjustment.
[0056] The voltage V
ref set by
R31 determines the average output power delivered to the lamp during steady state operation.
V
ref is adjusted to ~1.25V to maintain a constant 80 Watts delivered to the lamp. The
operating frequency of the PWM
U3 is set by
R30 and
C99 on the PWM (pins 6,7 of
U3). The frequency is set high enough to be out of range of human hearing, yet low enough
to reduce magnetically induced core energy losses in
L1-L2 and
L3-L4. Since the frequency is relatively high at 20 kHz, the 10% variation from the average
power delivered to the lamp (per switching cycle) is neither detectable by the human
eye, or by mechanical camera shutters whose shutter speed is limited to about 1 millisecond.
C67 connects to pin 9 of
U3, and is compensation capacitance to prevent a glitch on the PWM output.
[0057] Precise positioning of the arc at the focal point of the paraboloid reflector produces
a high intensity, high range, substantially parallel beam of light which is essentially
a portable spotlight with a 1 degree beam divergence; emitting ~1000 Lumens of the
~1200 Lumens generated by the xenon arc lamp (total lumens of visible light in the
range 380nm - 780nm) from a 4-inch diameter clear aperture. The beam is of long range,
typically as far as the eye can see; to enable the user to see objects at a distance
under reduced light conditions or darkness. The range of the lamp is typically greater
than one mile, and it has an intensity great enough to read when the spotlight is
illuminating a newspaper over your shoulder (in total darkness) from a distance of
one mile. In addition to being portable, the spotlight produces a beam, which will
penetrate fog and smoke by using an amber filter. An infrared filter allows for night
vision applications in the infrared (non-visible) range. The spotlight can be powered
from any convenient 10.5-14.5 Volt battery source, such as an automobile having a
12 Volt cigar lighter.
Mode 9. Safety Switch.
[0058] In order to protect the user from inadvertently leaving the thumb switch in the "on"
position and igniting the lamp during connection of the battery cable, a safety circuit
has been included which prevents inadvertent ignition. The safety switch can be left
on, and to ignite the lamp, it must be pressed to the "Start" position manually by
the user. The switch also has an "Off" position for added protection. Referring to
Figure 4, a mechanical thumb switch for OFF-NONE-MOMENTARY ON operation represents
SW
on and SW
off (SW
on or SW
off can be closed connections, but not both at the same time).
U2 pin 13 is a secondary latch that resets low anytime the battery is plugged in; disabling
the power supply and PWM
U3. When pin 13 of
U2 goes high due to engaging the switch to "start", the safety switch circuitry
145 bootstraps the PWM
148 and servo
149 into operation. When a battery is first connected to the circuit (with thumb switch
in either "Off" two or "Run" position), the safety switch circuit
145 sees voltage Vcc as the input voltage of
U2 pin 3. When the battery is first connected, pin 10 of
U2 becomes Vcc/3.2, while pin 11 of
U2 stays at zero. Since the voltage at pin 10 is greater than the voltage at pin 11
the output pin 13 of
U2 is in the low impedance state and the voltage at
U2 pin 13 remains near zero. Capacitor
C44 in conjunction with resistors
R42,R43,and R44 delays the onset of voltage to
U2 pin 11 when the battery is first connected; which assures pin 11 of
U2 stays near zero during any transients generated during battery connection. Once steady
state has been achieved (when the lamp is still off) in the short time before the
user is able to turn the power switch on ,
U2 pin 2 is high as
U2 pin 5 is at a voltage determined by
R78,R79 and
U2 pin 4 is low as described previously. With
U2 pin 2 in the high impedance state, it keeps the transistor
Q1 in cut-off so no collector current flows and the PWM remains without power. To then
turn the lamp on, SW
off is disengaged by moving the thumb switch and
U2 pin 11 remains at zero volts when the thumb switch is in the no contact ("None,"
or "Run") thumb switch position.
[0059] When the user finally pushes the thumb switch to the "Start" position, SW
on engages and causes
U2 pin 10 to become near zero, less than
U2 pin 11, subsequently
U2 pin 2 goes high as the small voltage at pin 11 becomes relatively large; although
still being only millivolts. This voltage differential causes
U2 pin 13 to attain 2*Vcc/3 which is both large enough to prevent forward conduction
of
D98 when the PWM is operating, and for
U2 pin 2 to go low. As soon as
U2 pin 2 goes low, a base current flows through
R46 thereby enabling current flow into the PWM pin 15 from the collector of
Q1 and subsequent lamp ignition as described in part 3 above. During operation of the
lamp, when the switch is in the "Run" position
U2 pin 10 remains at Vcc/3.2 and
U2 pin 11 remains at Vcc/3 hence the lamp continues to operate normally. During operation
of the lamp, when the switch is depressed to the "Start" position, the spark gap
EC1 can not fire as described above, so no ignition will occur. Only by depressing the
thumb switch to the "Off" position (when
U2 pin 11 goes low) can the output
U2 pin 13 go low to disable the lamp by terminating power to
U3 pin 15 (when
U2 pin 2 goes high). When the lamp has been shut off, the thumb switch can again be
switched to the "Run" and then "Start" positions to restart the lamp as described.
Mode 10. Low Battery Indicator Light.
[0060] During steady state operation, the PWM produces a regulated 5 Volts which appears
at
U2 pin 9 as 2.5 Volts using
R76-R77. If the voltage at pin 8 of
U2 decreases below 2.5 Volts, then
U2 pin 14 will go high and thereby provide base current to
Q2 via resistor
R02 and pull-up resistor
R01. The base current into
Q2 lights LED which has an internal current limiting resistor. Using a 12V, 12 Amp-Hour
lead acid battery sourcing 8-12 Amperes, it was found that the indicator lamp remains
on for ~5 minutes before the battery voltage becomes low enough to trigger the discharge
of
C40 into pin 1 of
U1; thereby disabling the PWM output
U3 pin 12 and shutting off the lamp. When the battery is first connected, the LED will
be disabled as the Voltage at
U2 pin 9 remains zero until the thumb switch is engaged to bootstrap
U3.
Mode 11. Elapsed time meter.
[0061] The elapsed time meter described in Figures 5 and 6 runs whenever the PWM
148 is powered up. When 400 hours has elapsed, the user can replace both the elapsed
time meter and the lamp. Continued usage beyond 400 hours presents an increased risk
of lamp explosion and collateral damage to the reflector and lens.
[0062] Although a preferred embodiment of the invention for a 75-Watt Xenon arc lamp (and
Xenon lamps in general) has been described above by way of example only, it will be
understood by those skilled in the art that modifications may be made to the disclosed
embodiment without departing from the scope of the invention, which is defined by
the appended claims.
[0063] The light from the device has been observed to cause a temporary stunning effect.
This stunning effect occurs within 2 seconds: the illuminated subject is observed
to temporarily lose the ability to see and to lose control of gross and fine motor
skills for approximately 10 minutes with full recovery within 30 minutes. The result
is disorientation and loss of balance effectively incapacitating the subject(s). No
physical damage to the visual system has been observed following exposure to the light
source.
[0064] The exact mechanism for the incapacitation is novel and appears to extend beyond
the transient decrease in vision that occurs in individuals when they are subjected
to the bright flash. There are more than 2 million neurons that comprise the optic
nerve. They constitute about 40% of the total number of nerves entering or leaving
the central nervous system via the cranial and spinal nerves. While the majority of
the neural information is destined for the visual cortex, the visual system also provides
a significant input for balance and muscle control. It is plausible that the incapacitation
is the result of a sensory overload of the brain.
Range Finder
[0065] A commercially available Infrared-based range finder may be interfaced with the device
of the present invention to increase its efficiency and effectiveness. For example
the LDM 301 (West Palm Beach, FL) or LRM Mod 2/2CI (Newcon Optik, Toronto, Ontario)
may be utilized in conjunction with the present invention. In one embodiment, the
range finder may output an analog voltage that is directly proportional to range that
would be used as the input to the device's power conversion and control electronics.
Alternatively, the interface between the range finder and the power conversion and
control electronics may be accomplished via a serial communication standard, such
as EIA-485, or similar.
Adjustable Lamp Power Control
[0066] It would be beneficial to be able to adjust the amount of power provided to the lamp
in circumstances where a target or targets may occur at variable distances from the
user. Increasing power to deliver an appropriate blast or flash at a distance to assure
incapacitation or decreasing the power during close proximity uses to save energy
would increase both efficiency and effectiveness. The power conversion and control
electronics consists of electronic circuitry that controls the operation of the lamp.
The three primary functions of the circuitry are lamp start, regulation of power during
lamp operation, and lamp shut down. In one embodiment, the power input to the lamp
is constant. In a preferred embodiment the power input to the lamp may be varied based
on the output of the range finder. The capability to vary the intensity of the visible
light output, as a function of range to the target and the optical beam width will
be performed by inputting an analog voltage output from the rangefinder into the device's
power conversion and control electronics. Alternatively, the interface between the
range finder and the power conversion and control electronics may be accomplished
via a serial communication standard, such as EIA-485, or similar.
Shutter
[0067] The activation and full high intensity illumination capability from an arc lamp can
take a moment after the arc has been initiated, consequently when initiating a blast
or flash it is preferable to have the lamp in its fully operational state before use.
Therefore, during acquisition of the target, a lens filter can be placed over the
lamp lens to spectrally limit its output to the near infrared. During illumination,
this lens filter can be removed, allowing the full visible spectrum illumination by
the lamp. In order for the target to be surprised, the lens filter must be removed
rapidly. This could be accomplished mechanically, using a fast acting shutter.
[0068] Alternatively, a separate Infrared only source could be used for the range finder
function. In that case, a shutter similar to that used in a camera could be utilized.
Operation
[0069] In one preferred embodiment the device of the present invention consists of a Xenon
short-arc lamp and associated optical components, a target ranging subsystem and a
power conversion and control electronics subsystem. If the system is to be utilized
at night it is preferable that night vision goggles be worn to more easily identify
targets.
[0070] The device will produce 3 million average candlepower of incoherent luminous intensity
in a tightly focused 1-degree beam that extends for a distance that can exceed one
mile. The beam can be adjusted as described above to provide a 10-degree beam spread
that provides an 885-foot diameter beam at 5,000 feet. Functionally, the operation
of the device consists of target acquisition, range finding, and illumination, generally
in sequence.
[0071] During operation the device is turned on and a particular target acquisition area
is then surveyed to select a target or targets. A detachable orange or black (870
or 980 nm) filter may be attached to the device, to provide enhanced illumination
for fog or night conditions, respectively. Once identified or selected the trigger
on the device is pulled one notch activating the spectrum of the device output to
a near infrared (850-nanometer wavelength). When activated the information received
from the reflection of the target's eyes, which is generally about 10dB above background
in both day and night conditions, will be communicated to the range finder for a calculation
of the distance to the target. That distance may be used to manually adjust the beam
width for the desired coverage by rotating the perimeter of the head portion of the
device. Alternatively the beam width and power input to the lamp may be adjusted automatically
by the power control electronics to a level that would provide a visible illumination
that is consistent with the measured target range and the user defined beam spread.
The device is then properly pointed at the target and the trigger pulled to it's final
stop. The target would be instantly illuminated and incapacitated by high-intensity
incoherent visible light for approximately twenty minutes and could be apprehended
with relative ease.